Ir-186 has been restudied through the Hf-180(B-11,Sn) reaction at 65 MeV using in-beam gamma-ray and conversion-electron spectroscopy. The unfavored component of the doubly decoupled band was established and shown to be consistent with a description in terms of the pi(9/2)circle times nu[<(411)over tilde> 1/2,3/2] structure, i.e., the coupling of an aligned proton and a neutron pseudospin doublet.

High-spin states in Lu-162 and Lu-164 have been studied by means of in-beam gamma-ray spectroscopy techniques using the multidetector array GASP. The excited states have been populated through the La-139(Si-28,5n)Lu-162 and La-139[(29(30))Si,4(5)n]Lu-164 reactions. Level schemes were constructed for both nuclei. Configurations for the rotational bands have been discussed. Alignments, band crossing frequencies, and B(M1)/B(E2) ratios have been analyzed in the framework of the cranking model. The systematic evolution of the signature inversion in the pi h(11/2)x nu i(13/2) structure is reviewed.

A 4π Si-ball detector system has been constructed as a trigger device for the γ-ray spectrometer GASP. The construction and operation of the detector is reported, together with a brief description of the electronics and of the data acquisition system used. Results are presented for the 32S + 40Ca reaction at 140 MeV of32S beam energy.

The ridge structure at $\ensuremath{\Delta}{E}_{\ensuremath{\gamma}}=\ifmmode\pm\else\textpm\fi{}$30 keV, observed previously in the reaction 187 MeV ${}^{37}\mathrm{Cl}{+}^{120}$Sn and attributed to an hyperdeformed nuclear shape, has been studied in a high statistics proton-$\ensuremath{\gamma}$ coincidence experiment. The presence of the ridge is confirmed but it is correlated to a set of $\ensuremath{\gamma}$-ray energies different from those proposed in earlier works. Some discrete transitions associated with this structure, which accounts for only $\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ of the fusion evaporation cross section, are proposed.

The study of superdeformation in nuclei around the nucleus 144Gd, which can be considered as doubly-closed at superdeformed shape, provided detailed knowledge about the structure of superdeformed bands in this region. The chain of Gd isotopes showing superdeformation could be extended to 143Gd. Since highly-deformed bands are known in 139,141Gd, it appears that the transition between the regions of superdeformed nuclei with A ≈ 150 and of highly-deformed nuclei with A ≈ 130 is rather sharp and takes place around N = 78 as theoretically predicted. In 144Gd four excited superdeformed bands have been found in addition to the yrast superdeformed band. They form two pairs of signature partner bands of π6 1 π[404]9 2ν7 0 and π6 1 π[411]3 2ν7 0 configurations. In 145Gd for the first time two crossings have been observed in a superdeformed band, which are assigned to the alignment of an i 13 2 proton pair and a subsequent crossing of the i 13 2 [642]5 2 and i 11 2 [651]1 2 neutron orbitals, respectively.

High-spin structures in 136Nd have been investigated via the 110Pd(30Si,4n) reaction at 125 MeV using the GASP array. Several bands consisting of stretched quadrupole transitions were identified. Two of them reach spins comparable to those of the highly-deformed (HD) band in 136Nd, which is based on a neutron i132-h92f72 configuration. Total routhian surface (TRS) calculations indicate that regular high-spin excitations in this γ-soft nucleus, can be also generated through successive pairs of h112 protons and neutrons coupled to a stable small-deformation triaxial core. The previously reported γ-ray transitions of an excited HD band, identical to the yrast HD band, are not confirmed by our data.

The \ensuremath{\gamma} cascades feeding into low-K and high-K bands in ${}^{163}$Er are investigated analyzing variances and covariance of the spectrum fluctuations. From a large data set of 1${0}^{9}$ triple coincidences, \ensuremath{\gamma}-\ensuremath{\gamma} coincidence spectra gated by resolved low-lying rotational bands are analyzed. Low-K bands are found to be fed by a much larger effective number of cascades than high-K bands. The covariance between pairs of gated spectra shows that the cascades feeding low-K bands are different from those feeding the high-K bands. The persistence of the K-selection rules for the excited rotational bands within the angular momentum region $30\ensuremath{\Elzxh}\ensuremath{\le}I\ensuremath{\le}40\ensuremath{\Elzxh}$ is suggested as explanation.

Lifetimes of excited states in Ba-126 have been measured with high precision by means of the GASP spectrometer using the coincidence recoil distance technique. The reaction Mo-100(Si-30,4n) Ba-126 at a beam energy of 130 MeV was used. The data were analyzed with the differential decay-curve method (DDCM). The obtained transition quadrupole moments disagree with the predictions of the asymmetric rotor model (ARM), the interacting boson model (IBM), and the general collective model (GCM). They give evidence for a sudden dynamic shape change in Ba-126 between the 4(+) and 10(+) levels of the ground-state band.

The $^{68}\mathrm{Ni}$ nucleus has been identified among the products of deep-inelastic reactions of $^{64}\mathrm{Ni}$ projectiles bombarding $^{130}\mathrm{Te}$ and $^{208}\mathrm{Pb}$ targets. Three new states, including the high-lying ${2}^{+}$ (2033 keV) and the 0.86 ms ${5}^{\ensuremath{-}}$ isomer, indicate a substantial subshell closure at neutron number $N=40$. The level structure and the observed very slow $E3$ transition speed are discussed within the shell model.

Very proton rich nuclei in the A approximate to 100 region have been investigated using the GASP array coupled with the Recoil Mass Spectrometer (RMS) and the GASP Si-ball. High-spin states of Sn-105 and In-103 nuclei formed with the reaction Ni-58 + Cr-50 at 210 MeV have been investigated up to approximate to 10 and 7 MeV of excitation energy respectively. We have confirmed the known excited states for both nuclei and extended to higher spin the level scheme. The experimental level schemes are compared with shell model calculations.

Very proton rich nuclei in the A approximate to 100 region have been investigated using the GASP array coupled with the Recoil Mass Spectrometer (RMS) and the GASP Si-ball. High-spin slates of Sn-105 rind In-103.105 nuclei formed with the reaction Ni-58 + Cr-50 at 210 MeV have been investigated up to approximate to 10 and 7 MeV of excitation energy respectively. We have confirmed the known excited states for both nuclei and extended to higher spin the level scheme. The experimental level schemes are compared with shell model calculations.

Unfavored components of doubly decoupled bands are reported for the first time. They can be interpreted as having the pseudo-spin flipped relative to the orientation in the favored components, i.e. antialigned with respect to the rotation axis. In addition, the differences in consecutive transition energies along the favored and unfavored sequences are strikingly similar among them up to Iπ = 15+and 14+ respectively. This feature arises from a cancellation of differences in alignments and moments of inertia.

Ten transitions linking the superdeformed band to the normal deformed states have been identified in 133-Nd. These transitions drain the full band intensity into the different band structures established at lower spin. The major part of the decay out of the superdeformed band is understood in terms of mixing of levels which involve orbitals differing by two major oscillator quantum numbers.

Transitions linking the highly deformed band to low deformation states have been unambiguously established in 133Nd in the very first experiment performed with the GASP array. The highly deformed band becomes yrast at 29/2+, where it mixes with the positive parity band built upon the [404]7/2 Nilsson state. The experimentally deduced interaction amounts to 13 keV. The measurement of the spins in the highly deformed intruder band sheds some light upon the reported backbend anomaly in this mass region.